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Diabetic Foot Problems: Keys to Effective, Aggressive Prevention

Diabetic Foot Problems: Keys to Effective, Aggressive Prevention

About 21 million Americans have diabetes mellitus.1 In 2002, an estimated $92 billion, or nearly 11% of health care costs in the United States, was spent on the treatment of diabetes and diabetic complications.2 Approximately one fourth of this amount was used in the management of foot and leg problems.3 Diabetic foot wounds are the leading cause of lower extremity amputations in the United States.4 Yet, when effective preventive measures are implemented, many such wounds can be avoided. With prompt and aggressive therapy, most diabetic foot and leg wounds that do occur can be resolved.

Here we discuss the various causes of diabetic foot problems and describe interventions that can prevent wounds from occurring.

CAUSES OF DIABETIC FOOT PROBLEMS
Indirect causes. Neuropathy and peripheral vascular disease are indirect causes of many diabetic foot wounds (Table 1). The absence of pain can result in a patient's failure to recognize a problem or to appreciate a problem's significance. Peripheral vascular disease can impair healing and promote infection; thus, a minor wound can progressively worsen, often to the point where it does not heal.

             
  Table 1 – Conditions that contribute to diabetic foot wounds  
             
  Condition   Wound consequences   Comments  
 
     
  Direct causes          
 
     
  Spurs, bunions, bunionettes, bosses   Ulcerations, infections   Result from bone responses to repetitive stresses, muscle imbalances, hereditary factors, or combinations of these  
 
     
  Clawed toes   Perforating ulcers and ulcerations over toe joints   Caused by imbalances in tone and strength of intrinsic and extrinsic toe muscles  
 
     
  Repetitive stresses   Formation of bursae; tissue breakdown; eventually erythema and ulcerations   Especially rapid occurrence of ulcerations when stresses involve high contact pressures  
 
     
  Overt injury   Bone and joint deformities generate sites of pressure concentration with loading; these may cause ulcers to develop from inside to outside   May initially go unrecognized in the neuropathic foot and ankle; common in Charcot arthropathy  
 
     
  Indirect causes          
  Peripheral vascular disease   Insufficient perfusion to meet metabolic demands of wound prevention and healing   Metabolic demands of healing are 20 times greater than requirements for maintenance of a steady state  
 
     
  Neuropathy   Muscle weakness may cause deformity and an abnormal gait pattern; loss of protective sensation may delay recognition of the problem   Deformities and loss of protective sensation contribute to the direct causes listed above  
 
     
  Skin dryness, atrophy, and soft tissue padding resorption from autonomic nerve dysfunction; toe nail problems   Increased vulnerability to wounds   Preventive measures are easily performed; attention to these is a measure of a patient's adherence  
 
   

Many experts believe that sensory neuropathy is responsible for the majority of diabetic foot wounds; however, sensory neuropathy must be placed in perspective. Wound recurrences are rare in motivated patients who have been educated about diabetic foot care—regardless of the degree of neuropathy. Treatment failure and leg amputation most often result from severe peripheral vascular disease, not from neuropathy.

Other conditions that can contribute to treatment failures include uncontrolled edema, capillary basement membrane thickening (a component of microangiopathy), impaired red blood cell deformability, autosympathectomy, hypoxia at the microcirculation level that results in a chemically mediated reperfusion insult, and the osmotic and glycosylation effects of hyperglycemia. Vasoconstriction resulting from cigarette smoking also interferes with blood flow and wound oxygenation.

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